Improved zinc oxide film for gas sensor applications

Zinc oxide (ZnO) is a versatile material for different commercial applications such as transparent electrodes, piezoelectric devices, varistors, SAW devices etc because of its high piezoelectric coupling, greater stability of its hexagonal phase and its pyroelectric property. In fact, ZnO is a potential material for gas sensor applications. Good quality ZnO films were deposited on glass and quartz substrates by a novel CVD technique using zinc acetate as the starting solution. X-ray diffraction confirmed the crystallinity of the zinc oxide film and SEM study revealed uniform deposition of fine grains. Undoped ZnO films were used for detection of dimethylamine (DMA) and H-2 at different temperatures by recording the change in resistivity of the film in presence of the test gases. The response was faster and the sensitivity was higher compared to the earlier reported ZnO based sensors developed in our laboratory. The main objective of this work was to study the selectivity of the ZnO film for a particular gas in presence of the others. The operating temperature was found to play a key role in the selectivity of such sensors.